Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. As such, tremendous emphasis is often placed on well access in the hydrocarbon recovery industry. That is, access to a well at an oilfield for monitoring its condition and maintaining its proper health is of great importance. As described below, such access to the well is often provided by way of coiled tubing.
Coiled tubing may be configured to deliver interventional or monitoring tools downhole and it may also accommodate fluid through its interior for a host of downhole applications. Furthermore, coiled tubing is particularly well suited for being driven downhole, to depths of perhaps several thousand feet, by an injector at the surface of the oilfield. Thus, with these characteristics in mind, the coiled tubing will also generally be of sufficient strength and durability to withstand such applications. For example, the coiled tubing may be of stainless steel or other suitable metal based material.
In spite of being constructed of a relatively heavy metal based material, the coiled tubing is plastically deformed and wound about a drum to form a coiled tubing reel. In this manner, the coiled tubing may be manageably delivered to the oilfield for use in a well thereat. Once positioned at the oilfield, the coiled tubing may be unwound from the reel and directed through the well by way of the noted injector equipment at the oilfield surface. However, due to the noted plastifying deformation, a residual bend is left in the coiled tubing as it is unwound for use. For certain applications, this residual bend may pose a problem. For example, in the case of highly deviated wells or extended reach wells of tens of thousands of feet in depth, it is likely that the bend in the coiled tubing will eventually result in helical locking up of the coiled tubing. Ultimately, this lock up will prevent the injector from driving the coiled tubing any further through the well. Thus, the coiled tubing may fail to reach the application site in the well.
In order to prevent helical lock up of coiled tubing in applications run in deviated or deep wells, the injector may be specially fitted with a reverse bend mechanism. The reverse bend mechanism may be a large heavy tool that is integrated into the body of the injector and configured to bend the coiled tubing in a manner opposite the plastifying deformation bend noted above. Thus, several thousand feet of coiled tubing may be straightened as it is run through the injector and driven downhole for the application.
Additionally, for many downhole applications, such as those targeting shallower depths in relatively vertical wells, the bent end of the coiled tubing may be problematic even though helical lock up may be of no significant concern. In such circumstances, the addition of a large and expensive reverse bend mechanism to the injector may accomplish little more than add to the weight and expense of equipment brought to the worksite.
Given the difficulty that a user encounters in feeding the bent end of the coiled tubing into the injector, a mobile, handheld reverse kinking mechanism is often employed by the user. The reverse kinking mechanism may be employed to reduce the amount of bend at the end of the coiled tubing thereby allowing the user to more easily feed the coiled tubing into the injector. For example, the user may slide the end of the coiled tubing through the mechanism a given amount and activate the mechanism. Activation of the mechanism involves physically inducing a kink, opposite the direction of the bend. This may be repeated in several isolated locations until the relatively uniform curvature at the end of the coiled tubing is replaced with a series of kinks that leave a repeating ‘w’ or corrugated appearance. While such ‘straightening’ is discontinuous and thus, not entirely straight, the now corrugated end of the coiled tubing may be easier for the user to manipulate and feed into the injector.
Unfortunately, corrugating the end of the coiled tubing with a reverse kinking mechanism as described above may still leave a difficult to manage coiled tubing end in certain regards. That is, while perhaps sufficient for feeding the injector, the user may deal with the end of the coiled tubing for a host of other reasons, some of which may call for a straighter coiled tubing end than the reverse kinking mechanism is able to provide. For example, a tool-string or even individual tools may be secured to the end of the coiled tubing for performance of monitoring and/or well intervention applications in the well. Securing such devices properly to the end of the coiled tubing may be critical to ensuring that the application is properly run without damage to, or loss of the devices. While the degree of bend may be reduced by the reverse kinking mechanism, in circumstances where the remaining bend in the coiled tubing end prevents a physically secure coupling of devices thereto, the user is placed in an unenviable predicament. That is, the user may be left with having to choose between risking device loss and having to re-run the application versus running the entire coiled tubing application through an otherwise unnecessary, more expensive and less available injector with incorporated reverse bend mechanism.